I can't solve this for the life of me, so I'm appealing to the Math Help Forum! Here's the question:

Let f(x) and g(y) be two differentiable functions and h(x,y)=f(x)+g(y) be with hx=sin(x) and hy=cos(x), and h(π/2,π/2)=5. Find h(x,y).

I have tried and tried, but I can't seem to solve it. I know that the partial w.r.t. y of y*cos(x) will give cos(x), but what do you add to get the partial w.r.t. x to get sin(x) as well? And what about that h(π/2,π/2)=5 part? HELP!